JP2019214639A - Rubber composition for tire, and pneumatic tire - Google Patents

Abstract

To provide a rubber composition for tire capable of improving low fuel consumption, wet grip performance and abrasion resistance in good balance, and a pneumatic tire using the same.SOLUTION: There is related a rubber composition for tire containing a rubber composition containing a styrene butadiene rubber with styrene amount of 25 mass% or more, an α-methyl styrene indene copolymer resin with weight average molecular weight of 400 or less, and silica, and having content of the α-methyl styrene indene copolymer resin of 0.1 to 100 pts.mass and content of the silica of 80 pts.mass based on 100 pts.mass of the rubber component.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition for a tire and a pneumatic tire.

Tires are required to have wet grip performance in order to ensure safety and the like. In order to meet this demand, styrene-butadiene rubber and silica have been widely used. However, when styrene-butadiene rubber is used, fuel economy and abrasion resistance tend to decrease.

Further, as a method of improving wet grip performance, a method of blending a resin such as an α-methylstyrene resin or a terpene resin is also known, and Patent Document 1 studies a resin containing a predetermined amount of indene. However, in recent years, further improvements have been required.

Japanese Patent No. 5424693

An object of the present invention is to solve the above problems and provide a rubber composition for a tire that can improve fuel economy, wet grip performance and abrasion resistance in a well-balanced manner, and a pneumatic tire using the same.

The present invention includes a rubber component containing a styrene-butadiene rubber having a styrene content of 25% by mass or more, an α-methylstyrene-indene copolymer resin having a weight average molecular weight of 400 or less, and silica, and 100 parts by mass of the rubber component. On the other hand, the present invention relates to a rubber composition for a tire, wherein the content of the α-methylstyrene / indene copolymer resin is 0.1 to 100 parts by mass and the content of the silica is 80 parts by mass or more.

The rubber composition preferably contains an indene resin having a weight average molecular weight of 400 or less.

The content of the styrene-butadiene rubber is preferably 10% by mass or more based on 100% by mass of the rubber component.

The rubber composition preferably contains silica having a nitrogen adsorption specific surface area of 170 to 300 m ² / g.

It is preferable that the content of the α-methylstyrene unit in the α-methylstyrene / indene copolymer resin is 15 to 70 mol%.

The present invention also relates to a pneumatic tire manufactured using the above rubber composition.

According to the present invention, a rubber component containing a styrene-butadiene rubber having a styrene content of 25% by mass or more, an α-methylstyrene-indene copolymer resin having a weight average molecular weight of 400 or less, and silica, and a rubber component of 100 parts by mass On the other hand, since the content of the α-methylstyrene-indene copolymer resin is 0.1 to 100 parts by mass and the content of silica is 80 parts by mass or more, the tire rubber composition has low fuel consumption and wet Grip performance and abrasion resistance can be improved in a well-balanced manner.

The rubber composition for a tire of the present invention includes a rubber component containing a styrene butadiene rubber (SBR) having a styrene content of 25% by mass or more, an α-methylstyrene-indene copolymer resin having a weight average molecular weight (Mw) of 400 or less, And 100 parts by mass of the rubber component, wherein the content of the α-methylstyrene / indene copolymer resin is 0.1 to 100 parts by mass, and the content of the silica is 80 parts by mass or more.

The rubber composition has the above-mentioned effects, which are presumed to be achieved by the following effects.
Since the α-methylstyrene / indene copolymer resin has styrene in the structure, it has high compatibility (affinity) with SBR having styrene in the structure, and can be easily dispersed in SBR. Moreover, it is difficult to separate from the SBR during traveling.
Further, since the α-methylstyrene / indene copolymer resin has a Mw of 400 or less, it easily bleeds at 10 to 30 ° C. corresponding to wet running.
Further, the α-methylstyrene-indene copolymer resin has a higher kinematic viscosity at 25 to 30 ° C. than that of a commonly used TDAE oil, and thus maintains a high Hs (hardness) of the rubber composition. can do. In addition, the grip is stable because the bleed is homogeneous compared to TDAE oil.
It is considered that the above actions improve fuel economy, wet grip performance and abrasion resistance in a well-balanced manner.

The rubber composition contains SBR as a rubber component.
The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), and the like can be used. Commercially available products such as Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., and Zeon Co., Ltd. can be used. These may be used alone or in combination of two or more.

The SBR may be either a non-modified SBR or a modified SBR.
The modified SBR may be any SBR having a functional group that interacts with a filler such as silica. For example, at least one terminal of the SBR is modified with a compound having the above functional group (a modifying agent). SBR (terminal modified SBR having the above functional group at the terminal), main chain modified SBR having the above functional group in the main chain, or main chain terminal modified SBR having the above functional group in the main chain and terminal (for example, A main chain terminal modified SBR having the above functional group and at least one terminal modified with the above modifying agent, or a polyfunctional compound having two or more epoxy groups in a molecule; And terminal-modified SBR into which an epoxy group has been introduced.

Examples of the functional group include, for example, amino group, amide group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide Group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group and the like. . Note that these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted by an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( Preferably, it is an alkoxysilyl group having 1 to 6 carbon atoms).

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一又は異なって、アルキル基、アルコキシ基、シリルオキシ基、アセタール基、カルボキシル基（−ＣＯＯＨ）、メルカプト基（−ＳＨ）又はこれらの誘導体を表す。Ｒ^４及びＲ^５は、同一又は異なって、水素原子又はアルキル基を表す。Ｒ^４及びＲ^５は結合して窒素原子と共に環構造を形成してもよい。ｎは整数を表す。） As the modified SBR, an SBR modified with a compound (modifier) represented by the following formula is particularly preferable.

(Wherein, R ¹ , R ² and R ³ are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof. R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or an alkyl group; R ⁴ and R ⁵ may combine with each other to form a ring structure together with a nitrogen atom;

As the modified SBR modified with the compound represented by the above formula (modifying agent), the polymerization end (active end) of the solution-polymerized styrene-butadiene rubber (S-SBR) is, among others, a compound represented by the above formula. A modified SBR (such as a modified SBR described in JP-A-2010-111753) is preferably used.

As R ¹ , R ² and R ³ , an alkoxy group is suitable (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). As R ⁴ and R ⁵ , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is suitable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. When R ⁴ and R ⁵ combine to form a ring structure together with a nitrogen atom, the ring is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

Specific examples of the modifier include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 2-diethylaminoethyltrimethoxysilane. Examples include methoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Among them, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferable. These may be used alone or in combination of two or more.

As the modified SBR, a modified SBR modified with the following compound (denaturing agent) can also be suitably used. Examples of the denaturing agent include two or more polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; and diglycidylated bisphenol A. Polyglycidyl ether of an aromatic compound having a phenol group of the following: 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, polyepoxy compound such as polyepoxidized liquid polybutadiene; 4,4′-diglycidyl-diphenyl Epoxy-containing tertiary amines such as methylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N, N'-diglycidyl-4-glycidyloxyaniline, diglycidyl Luso toluidine, tetraglycidyl meta-xylene diamine, tetraglycidyl diaminodiphenylmethane, tetraglycidyl -p- phenylenediamine, diglycidyl aminomethyl cyclohexane, diglycidyl amino compounds such as tetraglycidyl-1,3-bisaminomethylcyclohexane;

Amino group-containing acid chlorides such as bis- (1-methylpropyl) carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N, N-dimethylcarbamic acid chloride, N, N-diethylcarbamic acid chloride; 1 Epoxy-containing silane compounds such as, 3-bis- (glycidyloxypropyl) -tetramethyldisiloxane and (3-glycidyloxypropyl) -pentamethyldisiloxane;

(Trimethylsilyl) [3- (trimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (triethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (tripropoxysilyl) propyl] sulfide, (trimethylsilyl) [3 -(Tributoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldimethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldiethoxysilyl) propyl] sulfide, (trimethylsilyl) [3- (methyldiyl) Sulfide group-containing silane compounds such as propoxysilyl) propyl] sulfide and (trimethylsilyl) [3- (methyldibutoxysilyl) propyl] sulfide;

N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) -3-aminopropyltriethoxy Alkoxysilanes such as silane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) aminoethyltriethoxysilane; 4-N, N-dimethylaminobenzophenone, 4-N, N- Di-t-butylaminobenzophenone, 4-N, N-diphenylaminobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (diphenylamino ) Benzophenone, N, N (Thio) benzophenone compounds having an amino group and / or a substituted amino group such as N ', N'-bis- (tetraethylamino) benzophenone; 4-N, N-dimethylaminobenzaldehyde, 4-N, N-diphenylaminobenzaldehyde N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-methyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, and the like. N-substituted pyrrolidone such as -t-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone and the like N-substituted piperidones; N-methyl-ε-caprolactam, N-phenyl-ε-capro N-substituted lactams such as octamone, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, N-phenyl-β-propiolactam; other,

N, N-bis- (2,3-epoxypropoxy) -aniline, 4,4-methylene-bis- (N, N-glycidylaniline), tris- (2,3-epoxypropyl) -1,3,5 -Triazine-2,4,6-triones, N, N-diethylacetamide, N-methylmaleimide, N, N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3 -Diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N, N-dimethylaminoacetophene, 4-N, N-diethylaminoacetophenone, 1,3-bis (diphenyl Amino) -2-propanone, 1,7-bis (methylethylamino) -4-heptanone and the like.
The modification with the compound (denaturing agent) can be performed by a known method.

The styrene content of the SBR may be 25% by mass or more, but is preferably 26% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less. When it is in the above range, the compatibility (affinity) with the α-methylstyrene / indene copolymer resin tends to be particularly good.
In addition, the styrene content of SBR can be measured by ¹ H-NMR measurement.

The vinyl content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.
In addition, the vinyl amount (1,2-bonded butadiene unit amount) of SBR can be measured by infrared absorption spectrum analysis.

The content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 40% by mass or more, even more preferably 70% by mass or more, and preferably 90% by mass or less, more preferably It is 80% by mass or less. When the content is within the above range, entanglement with the α-methylstyrene / indene copolymer resin is likely to occur, and the effect tends to be obtained more favorably.

Examples of rubber components that can be used other than SBR include butadiene rubber (BR), isoprene-based rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). ) And the like. These may be used alone or in combination of two or more. Among them, BR and isoprene rubber are preferred.

The BR is not particularly limited. For example, BR having a high cis content (high cis BR), BR containing a 1,2-syndiotactic polybutadiene crystal (BR containing SPB), butadiene synthesized using a rare earth element catalyst Rubbers (rare earth BR), tin-modified butadiene rubber modified with a tin compound (tin-modified BR), and the like common in the tire industry are exemplified. The tin-modified BR is usually a low cis content BR (low cis BR). The BR may be either a non-modified BR or a modified BR. Examples of the modified BR include the modified BR into which the above-described functional group has been introduced. The modified BR may be either low cis BR or high cis BR. Commercially available products such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used. These may be used alone or in combination of two or more. From the viewpoint of abrasion resistance, a rare earth-based BR is preferable, and from the viewpoint of low fuel consumption, a modified BR is preferable.

As the rare-earth BR, conventionally known ones can be used. For example, a rare-earth element-based catalyst (a lanthanum-based rare-earth element compound, an organoaluminum compound, an aluminoxane, a halogen-containing compound, and a catalyst containing a Lewis base as needed) and the like are used. And those synthesized. Among them, butadiene rubber (Nd-based BR) synthesized using a neodymium-based catalyst using a neodymium (Nd) -containing compound as a lanthanum-based rare earth element compound is preferable.

The cis content of BR is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 97% by mass or more, and the upper limit is not particularly limited. When the content is in the above range, the effect tends to be more favorably obtained.
In addition, the cis content of BR can be measured by an infrared absorption spectrum analysis method.

The vinyl content of BR is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less, and the lower limit is not particularly limited. When the content is in the above range, the effect tends to be more favorably obtained.
In addition, the vinyl amount of BR (1,2-bonded butadiene unit amount) can be measured by an infrared absorption spectrum analysis method.

The glass transition temperature (Tg) of BR is preferably -160C or higher, more preferably -130C or higher, and is preferably -60C or lower, more preferably -90C or lower.
The glass transition temperature of BR is a value measured according to JIS-K7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan, Inc. at a heating rate of 10 ° C./min. It is.

When BR is contained, the content of BR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 90% by mass or less, more preferably 60% by mass. %, More preferably 30% by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. NR can be SIR20, RSS # 3, TSR20, etc., and IR can be IR2200, etc., which are common in the tire industry. Modified NR refers to deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., and modified NR refers to epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., and modified IR. Examples include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more.

When the isoprene-based rubber is contained, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 7% by mass or more, and preferably 30% by mass or less. Preferably it is 20 mass% or less. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition contains an α-methylstyrene-indene copolymer resin having a weight average molecular weight (Mw) of 400 or less.
The α-methylstyrene / indene copolymer resin is a copolymer (copolymer) containing α-methylstyrene-derived structural units (α-methylstyrene units) and indene-derived structural units (indene units) as main components. Liquid at normal temperature (25 ° C.), for example, a dimer composed of one α-methylstyrene and one indene, two α-methylstyrenes and one indene, or α-methylstyrene And a trimer composed of one methylstyrene and two indene. One of these may be used alone, or two or more may be used in combination, but it is preferable to use two or more in combination.
The α-methylstyrene / indene copolymer resin can be produced by a general polymerization method.

The Mw of the α-methylstyrene / indene copolymer resin may be 400 or less, but is preferably 380 or less, and is preferably 150 or more, and more preferably 200 or more. Within the above range, appropriate kinematic viscosity and blooming tend to be obtained.
Mw is based on the value measured by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGLEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation). Can be determined by standard polystyrene conversion.

The content of the α-methylstyrene unit in the α-methylstyrene-indene copolymer resin is preferably 15 mol% or more, more preferably 30 mol% or more, and preferably 70 mol% or less, more preferably Is 65 mol% or less. When it is in the above range, the compatibility (affinity) with SBR tends to be particularly good.
From the same viewpoint, the total content of the α-methylstyrene unit and the indene unit in the α-methylstyrene / indene copolymer resin is preferably 80 mol% or more, more preferably 90 mol% or more, and further preferably 95 mol% or more. Mol% or more, and may be 100 mol%.

The content of the α-methylstyrene-indene copolymer resin with respect to 100 parts by mass of the rubber component may be 0.1 to 100 parts by mass, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and It is preferably at least 15 parts by mass, particularly preferably at least 20 parts by mass, and preferably at most 50 parts by mass, more preferably at most 40 parts by mass. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition preferably contains an indene resin having a weight average molecular weight (Mw) of 400 or less. Since the indene resin has high polarity, it is difficult to disperse in rubber alone. However, when used in combination with the α-methylstyrene / indene copolymer resin, the indene resin can be well dispersed in rubber. Then, by uniformly dispersing the indene resin in the rubber, the amount and viscoelasticity of the bleed material (bleed film) formed on the rubber surface are increased, and the wet grip performance can be further improved.
The indene resin is a polymer or a copolymer containing indene units as a main component and is a liquid at ordinary temperature (25 ° C.). For example, a dimer composed of two indenes or a trimer composed of three indenes Trimer and the like. One of these may be used alone, or two or more may be used in combination, but it is preferable to use two or more in combination.
The indene resin can be produced by a general polymerization method.

Mw of the indene resin may be 400 or less, preferably 380 or less, more preferably 150 or more, and more preferably 200 or more. Within the above range, an appropriate kinematic viscosity tends to be obtained.

In the indene resin, the content of the indene unit is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and may be 100 mol%. When the content is in the above range, the effect tends to be more favorably obtained.

When the indene resin is contained, the content of the indene resin relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably Is 15 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.
From the same viewpoint, the total content of the α-methylstyrene-indene copolymer resin and the indene resin relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more. It is at least 20 parts by mass, particularly preferably at least 20 parts by mass, preferably at most 50 parts by mass, more preferably at most 40 parts by mass.

The rubber composition may contain another resin in addition to the α-methylstyrene / indene copolymer resin and the indene resin. Other resins are not particularly limited as long as they are widely used in the tire industry, and include styrene resins, terpene resins, rosin resins, coumarone indene resins, pt-butylphenol acetylene resins, and acrylic resins. , C5 resin, C9 resin and the like. Commercial products include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals, BASF, Arizona Chemical Co., Nikki Chemical Co., Ltd., Japan Co., Ltd. Catalysts, products of JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd. and the like can be used. These may be used alone or in combination of two or more.

The rubber composition contains silica.
Examples of the silica include dry process silica (silicic anhydride) and wet process silica (hydrous silicic acid). However, wet process silica is preferable because it has many silanol groups. Commercially available products such as Degussa Co., Rhodia Co., Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Co., Ltd. can be used. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 170 m ² / g or more, more preferably 200 m ² / g or more, further preferably 230 m ² / g or more, particularly preferably 250 m ² / g or more. Further, it is preferably at most 300 m ² / g, more preferably at most 280 m ² / g. When the content is in the above range, the effect tends to be more favorably obtained.
In addition, the nitrogen adsorption specific surface area of silica is a value measured by a BET method according to ASTM D3037-81.

When silica (fine particle silica) having N ₂ SA of 200 m ² / g or more is used, Hs and viscosity of the rubber composition increase, so that it is necessary to reduce the amount of silica. Tends to worsen. On the other hand, in the rubber composition, by blending the α-methylstyrene / indene copolymer resin, good wet grip performance can be secured even if the amount of silica is reduced.
Further, when the fine particle silica is used, the Hs and the viscosity of the rubber composition may not be able to be adjusted to an appropriate range only by reducing the amount of silica in some cases. However, in the rubber composition, the α-methylstyrene. By blending the indene copolymer resin, Hs and viscosity of the rubber composition can be adjusted to appropriate ranges.

The content of silica with respect to 100 parts by mass of the rubber component may be 80 parts by mass or more, preferably 90 parts by mass or more, and preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and still more preferably. Is 120 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition preferably contains a silane coupling agent. Thereby, the effect tends to be better obtained.
The silane coupling agent is not particularly limited, and includes, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilyl) B) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, Sulfides such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT manufactured by Momentive, and mercapto such as NXT-Z; vinyltriethoxysilane; vinyl Vinyls such as trimethoxysilane, aminos such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycid Glycidoxy type such as cypropyltrimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro type such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane And so on. Commercially available products such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd., and Dow Corning Toray Co., Ltd. can be used. These may be used alone or in combination of two or more.

When a silane coupling agent is contained, the content of the silane coupling agent is preferably at least 3 parts by mass, more preferably at least 6 parts by mass, and preferably at least 15 parts by mass, per 100 parts by mass of silica. Or less, more preferably 10 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition preferably contains carbon black. Thereby, the effect tends to be better obtained.
It does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. are mentioned. As commercial products, use products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. it can. These may be used alone or in combination of two or more.

When carbon black is contained, the content of carbon black is preferably at least 3 parts by mass, more preferably at least 5 parts by mass, and preferably at most 30 parts by mass, based on 100 parts by mass of the rubber component. Preferably it is 15 parts by mass or less. When it is within the above range, the effect can be more suitably obtained.

The rubber composition may include an oil.
Oils include, for example, process oils, vegetable fats and oils, or mixtures thereof. As the process oil, for example, a paraffin-based process oil, an aroma-based process oil, a naphthene-based process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, bean oil, sesame oil, Olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. These may be used alone or in combination of two or more.

Since the α-methylstyrene-indene copolymer resin is liquid at normal temperature (25 ° C.), by blending it with the rubber composition, the amount of oil can be reduced, and the fuel efficiency and the like can be further improved. In the rubber composition, the oil content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and still more preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. There may be.

The rubber composition may include a wax.
Examples of the wax include, but are not particularly limited to, petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; and synthetic waxes such as polymers such as ethylene and propylene. As commercial products, products of Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

When a wax is contained, the content of the wax is preferably at least 1 part by mass, more preferably at least 2 parts by mass, and preferably at most 20 parts by mass, more preferably at most 20 parts by mass, based on 100 parts by mass of the rubber component. 10 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition may include an antioxidant.
Examples of the antioxidant include naphthylamine antioxidants such as phenyl-α-naphthylamine; diphenylamine antioxidants such as octylated diphenylamine and 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine; -Isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine and the like P-phenylenediamine antioxidants; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methylphenol; Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3 ', 5'-di-t-butyl- '- hydroxyphenyl) propionate] bis methane, tris, polyphenolic antioxidants, and the like. As commercially available products, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Flexis and the like can be used. These may be used alone or in combination of two or more. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred.

When the antioxidant is contained, the content of the antioxidant is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and preferably at most 10 parts by mass, based on 100 parts by mass of the rubber component. , More preferably 8 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition may contain a fatty acid, especially stearic acid.
Conventionally known stearic acid can be used, and commercially available products include products such as NOF Corporation, NOF, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Corporation. Can be used. These may be used alone or in combination of two or more.

When stearic acid is contained, the content of stearic acid is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and preferably at most 10 parts by mass, based on 100 parts by mass of the rubber component. It is preferably at most 5 parts by mass. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition may contain zinc oxide.
Conventionally known zinc oxide can be used, and commercially available products include Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusuiteku Co., Ltd., Shodo Chemical Co., Ltd., Sakai Chemical Industry Co., Ltd. And other products can be used. These may be used alone or in combination of two or more.

When zinc oxide is contained, the content of zinc oxide is preferably at least 1 part by mass, more preferably at least 2 parts by mass, and preferably at most 10 parts by mass, based on 100 parts by mass of the rubber component. It is preferably at most 5 parts by mass. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition may contain sulfur.
Examples of the sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. Commercially available products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Kishii Kogyo Co., Ltd. and Hosoi Chemical Co., Ltd. can be used. These may be used alone or in combination of two or more.

When sulfur is contained, the sulfur content is preferably at least 0.6 part by mass, more preferably at least 1 part by mass, and preferably at most 5 parts by mass, based on 100 parts by mass of the rubber component. It is preferably at most 3 parts by mass. When the content is in the above range, the effect tends to be more favorably obtained.

The rubber composition may contain a vulcanization accelerator.
Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), thiuram-based vulcanization accelerators such as tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfena De-based vulcanization accelerator; diphenylguanidine, may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. Commercially available products such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. can be used. These may be used alone or in combination of two or more.

When a vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably at least 1 part by mass, more preferably at least 2 parts by mass, and preferably at least 10 parts by mass, per 100 parts by mass of the rubber component. Or less, more preferably 8 parts by mass or less. When the content is in the above range, the effect tends to be more favorably obtained.

In the rubber composition, in addition to the above components, additives generally used in the tire industry, for example, organic peroxides; fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica And the like may be further added. The content of these additives is preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 to 180 ° C, preferably 120 to 170 ° C. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120 ° C or lower, preferably 85 to 110 ° C. The composition obtained by kneading the vulcanizing agent and the vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190 ° C, preferably 150 to 185 ° C. The vulcanization time is usually 5 to 15 minutes.

The rubber composition is suitably used for a tread (cap tread), but is used for covering members other than the tread, for example, a sidewall, a base tread, an undertread, a clinch apex, a bead apex, a breaker cushion rubber, and a carcass cord. It may be used for rubber, insulation, chafer, inner liner, etc., or a side reinforcing layer of a run flat tire.

The pneumatic tire of the present invention is manufactured by a usual method using the above rubber composition.
That is, the above rubber composition is extruded according to the shape of each tire member at the unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine, thereby obtaining an unvulcanized material. Form the tire. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

The pneumatic tire can be used for passenger car tires, truck / bus tires, motorcycle tires, high-performance tires, and the like, and is particularly suitable for passenger car tires.

The present invention will be specifically described based on examples, but the present invention is not limited to these.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
The α-methylstyrene / indene copolymer resins 1 to 6, the indene resins 1 and 2, the α-methylstyrene resins 1 and 2 and the styrene / indene copolymer resins 1 and 2 are obtained by gel permeation chromatography This is a prototype taken from (GPC).
<NR>
TSR20
<BR>
LANXESS CB25 (BR synthesized using an Nd-based catalyst (Nd-based BR), cis content: 97% by mass, vinyl content: 0.7% by mass, Tg: -110 ° C)
<Modified SBR for silica>
Terminal-modified SBR prepared in Production Example 1 below (styrene content: 27% by mass, vinyl content: 58% by mass, modifier: R ¹ , R ² and R ^{3 in the} above formula = —OCH ₃ , R ⁴ and R ⁵ = -CH _3, n = ₃₎
<Carbon black N220>
Showbot N220 (N ₂ SA: 114 m ² / g) manufactured by Cabot Japan Co., Ltd.
<Silica 1>
Z1085Gr (N ₂ SA: 80 m ² / g) manufactured by Solvay
<Silica 2>
Ultrasil VN3 manufactured by Evonik Degussa (N ₂ SA: 175 m ² / g)
<Silica 3>
Premium SW (N ₂ SA: 275 m ² / g) manufactured by Solvay
<Silica 4>
U9000 manufactured by Evonik Degussa (N ₂ SA: 235 m ² / g)
<Α-methylstyrene-indene copolymer resin 1>
Prototype (a dimer composed of one α-methylstyrene and one indene, Mw: 236, content of α-methylstyrene unit: 50 mol%)
<Α-methylstyrene-indene copolymer resin 2>
Prototype (trimer composed of one α-methylstyrene and two indene, Mw: 354, content of α-methylstyrene unit: 33 mol%)
<Α-methylstyrene-indene copolymer resin 3>
Prototype (trimer composed of two α-methylstyrenes and one indene, Mw: 354, α-methylstyrene unit content: 67 mol%)
<Indene resin 1>
Prototype (dimer composed of two indenes, Mw: 236)
<Indene resin 2>
Prototype (trimer composed of three indenes, Mw: 354)
<Α-methylstyrene resin 1>
Prototype (dimer composed of two α-methylstyrenes, Mw: 236)
<Α-methylstyrene resin 2>
Prototype (trimer composed of three α-methylstyrenes, Mw: 354)
<Α-methylstyrene-indene copolymer resin 4>
Prototype (tetramer composed of one α-methylstyrene and three indene, Mw: 472, content of α-methylstyrene unit: 25 mol%)
<Α-methylstyrene-indene copolymer resin 5>
Prototype (tetramer composed of two α-methylstyrenes and two indene, Mw: 472, α-methylstyrene unit content: 50 mol%)
<Α-methylstyrene-indene copolymer resin 6>
Prototype (pentamer composed of two α-methylstyrenes and three indenes, Mw: 590, α-methylstyrene unit content: 40 mol%)
<Styrene-indene copolymer resin 1>
Prototype (dimer composed of one styrene and one indene, Mw: 222)
<Styrene / indene copolymer resin 2>
Prototype (trimer composed of one styrene and two indenes, Mw: 340)
<Α-methylstyrene / styrene copolymer resin>
Sylvatraxx4401 (a copolymer of α-methylstyrene and styrene) manufactured by Arizona Chemical Company
<Aromatic modified terpene resin>
YS resin TO125 (copolymer of styrene and terpene compound, softening point: 125 ° C.) manufactured by Yashara Chemical Co., Ltd.
<Coumarone-indene copolymer resin>
Esculon V120 manufactured by Nikki Chemical Co., Ltd. (coumarone, indene, styrene and phenol copolymers (copolymers mainly composed of structural units derived from coal and structural units derived from petroleum), softening point: 120 ° C.)
<Process oil>
Vivatec 500 (TDAE oil) manufactured by H & R
<Paraffin wax>
Ozoace0355 manufactured by Nippon Seiro Co., Ltd.
<Antiaging agent 6PPD>
Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
<Antiaging agent TMQ>
Nocrack 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
<Stearic acid>
Stearic acid "Tsubaki" manufactured by NOF Corporation
<Zinc oxide>
Ginrei R manufactured by Toho Zinc Co., Ltd.
<Silane coupling agent>
Si75 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
<Sulfur>
HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Co., Ltd.
<Vulcanization accelerator TBBS>
Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
<Vulcanization accelerator DPG>
Noxeller D (diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

<Preparation of terminal modifier>
Under a nitrogen atmosphere, 20.8 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by AZMAX) was placed in a 250 ml volumetric flask, and anhydrous hexane (manufactured by Kanto Chemical Co., Ltd.) was added. Was made 250 ml.

<Production Example 1>
18 L of n-hexane, 540 g of styrene (manufactured by Kanto Chemical Co., Ltd.), 1460 g of butadiene, and 17 mmol of tetramethylethylenediamine were added to a 30 L pressure-resistant container sufficiently purged with nitrogen, and the temperature was raised to 40 ° C. Next, 3.5 ml of a 0.4 mol / L silicon tetrachloride / hexane solution was added, followed by stirring for 30 minutes. Next, after adding 10.5 mL of butyllithium, the temperature was raised to 50 ° C., and the mixture was stirred for 3 hours. Next, 30 mL of the above terminal modifier was added and stirred for 30 minutes. To the reaction solution was added 2 mL of methanol (manufactured by Kanto Chemical Co., Ltd.) in which 0.2 g of 2,6-tert-butyl-p-cresol (manufactured by Ouchi Shinko Chemical Co., Ltd.) was dissolved. The aggregate was collected in a stainless steel container containing methanol. The obtained aggregate was dried under reduced pressure for 24 hours to obtain a modified SBR for silica.

<Examples and comparative examples>
According to the formulation shown in Table 1, a chemical other than sulfur and a vulcanization accelerator was kneaded for 5 minutes at 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded with an open roll at 80 ° C. for 5 minutes to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press-vulcanized at 170 ° C. for 10 minutes to obtain a vulcanized rubber composition.
In addition, the obtained unvulcanized rubber composition was molded into a cap tread shape, bonded together with other tire members to produce an unvulcanized tire, and press-vulcanized at 170 ° C. for 10 minutes and tested. Tire (size: 195 / 65R15) was obtained.

The obtained vulcanized rubber composition and test tire were evaluated as follows. The results are shown in Table 1.
In the examples and comparative examples, the blending content is adjusted so that the hardness is within a certain range.

<Low fuel consumption>
Using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho, tan δ of the vulcanized rubber composition was measured at a temperature of 50 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%, and a comparative example was obtained. The index was expressed as an index with 1 as 100 (fuel efficiency index). The larger the index, the smaller the tan δ and the better the fuel economy. It was judged to be good when the index was 105 or more.

<Wet grip performance>
The test tires were mounted on a 2000 cc domestic FR car with a displacement of 2000 cc, and the vehicle was run on the test course on wet asphalt road surface for 10 laps. At this time, the stability of the control at the time of steering was sensory evaluated by a test driver, and the index was displayed as an index with Comparative Example 1 being 100. A higher index indicates better wet grip performance. It was judged to be good when the index was 105 or more.

<Abrasion resistance>
The test tire was mounted on a 2000 cc Japanese FR car with a displacement of 2000 cc, and the vehicle was run on a test course on dry asphalt road surface. The vehicle mounting positions of the control tire and the test tire were exchanged every 1000 km, and the vehicle running factors to wear were averaged. The remaining groove amount of the tire tread rubber in the test tire after traveling 30,000 km was measured (8.0 mm at the time of a new product). The larger the index, the smaller the amount of abraded rubber and the better the abrasion resistance. It was judged to be good when the index was 105 or more.

From Table 1, the rubber component containing a styrene butadiene rubber having a styrene content of 25% by mass or more, an α-methylstyrene-indene copolymer resin having a weight average molecular weight of 400 or less, and silica, and 100 parts by mass of the rubber component Examples in which the content of the α-methylstyrene-indene copolymer resin is 0.1 to 100 parts by mass and the content of silica is 80 parts by mass or more have low fuel consumption, wet grip performance and abrasion resistance. The balance has been improved.

On the other hand, when an α-methylstyrene-indene copolymer resin having a weight average molecular weight of more than 400 was used, the performance was not improved but tended to decrease (Comparative Examples 8 to 11).

Claims (6)

A rubber component containing a styrene-butadiene rubber having a styrene content of 25% by mass or more;
Α-methylstyrene-indene copolymer resin having a weight average molecular weight of 400 or less,
Containing silica,
A rubber composition for a tire, wherein the content of the α-methylstyrene-indene copolymer resin is 0.1 to 100 parts by mass and the content of the silica is 80 parts by mass or more based on 100 parts by mass of the rubber component. The rubber composition for a tire according to claim 1, wherein the rubber composition comprises an indene resin having a weight average molecular weight of 400 or less. The rubber composition for a tire according to claim 1 or 2, wherein the content of the styrene-butadiene rubber is 10% by mass or more based on 100% by mass of the rubber component. The tire rubber composition according to any of claims 1 to 3 nitrogen adsorption specific surface area contains silica of 170~300m ² / g. The rubber composition for a tire according to any one of claims 1 to 4, wherein the α-methylstyrene / indene copolymer resin has an α-methylstyrene unit content of 15 to 70 mol%. A pneumatic tire produced using the rubber composition according to claim 1.